Method of forming fibrous pads

ABSTRACT

An air-laid fibrous web is confined between a lower foraminous support member and an upper pad engaging surface having a shape of a fibrous pad to be formed. A pressure differential is established across the foraminous support member for removing unconfined portions of the fibrous web to thereby form a fibrous pad underlying the pad-engaging surface and having substantially the same shape as the pad-engaging surface.

United- States Patent 1191 Savich Dec. 3, 1974 [5 METHOD OF FORMING FIBROUS PADS 3,366,115 H1968 Champaigne, Jr. 19/145 x 3,445,897 5 1969 F 19 144.5 [75] Inventor: Peter P. SavIch, Longmeadow, 3,518,726 711970 221 N Mass- 3,527,858 9/1970 Braxton et a1. 264/160 x [73] Assignee: Scott Paper Company, Delaware County, p Primary Examiner'D0rsey Newton Filed: Mar. 9 3 gglzgney, Agennvor Firm-Martin L. Faigus; William J. [21] Appl. No.: 337,932

[57] ABSTRACT 52 us. c1. 19/1445 air-laid fibrous Web is confined between a lower [51] Int. Cl A611 15/00 foraminous Support member and "PP Pad engag' 5s Field of Search 19/144, 145, 145.5, 148, M surface having a Shape of a fibrous P to be 4 19/1445; 425 049; 5 264/93 145 'formed. A pressure differential is established across 15 0 mg 7 156/622, 6234 625 the foraminous support member for removing unconfined portions of the fibrous web to thereby form a fi- 5 References Cited brous pad underlying the pad-engaging surface and UNITED STATES PATENTS having substantially the same shape as the pad engaging surface. 2,121,454 6/1938 Teall 19/145 2,926,394 3/1960 Bletzinger et a1 l9/l44.5

4 Claims, 2 Drawing Figures WEB FORMING DEVICE 1. Field of the Invention I This inventionrelates generally to method and apparatus for forming absorbent fibrous pads, and specifically to method and apparatus for forming absorbent fibrous pads suitable for use as an absorbent component in disposable products, such as disposable diapers,

- sanitary napkins and the like.

than a forward and rearward region thereof. Inaddition, such pads can be profiled to have a greater basis weight in one predetermined other predetermined regions.

U.S.Pat.'Application Ser. No. 237,963, assigned to Scott Paper Company, discloses a method and apparatus for forming shaped and/or profiled. fibrous pads. According to the teachings of the'above application, the pads are formed by directing a gaseous suspension of. substantially individualized fibers toward a formation assemblywhich includes three-dimensional padreceiving pad to be formed. A partial va'cuumis pulled through a foraminous bottom wallof each compartment to direct the gas of said suspensionthrough the bottom walls and deposit the fibers in the threedimensional compartments toform fibrous pads having substantially the same shape as said compartments. The pads formed in such three-dimensional compartments are sometimes difficult to remove, especially, if such compartments have sharp corners. The fibrous pads tend to cling to the side surfaces of the threeregion thereof than in dimensional compartments in the sharp corner regions,

'and cannot be easily removed from said compartments without damaging the formed pad. Also, high basis I 2 extremely difficult, if not impossible, to utilize the approach disclosed in the U.S. Pat. No. 3,661,680 to form discrete fibrous'webs which are spaceda relatively large distance apart. To accomplish this objective, the

outer shell would have to be exceptionally large to provide a large slot area overlying alarge area of the fibrous web for removing large sections of said web. Practical space limitations might prevent the use of such a large outer shell.

SUMMARY OF THE. lNvENTioN Method and apparatus of this invention for forming at least one discrete fibrous pad from an air-laid fibrous web'employ at least one pad-formingshoe having a pad-engaging surface with the same predetermined shape as a fibrous pad to be formed. The fibrous web is confined between a support member and the padengaging surfaces of the pad-forming shoes, and unconfined portions of the fibrous web are removed to form fibrous pads underlying the'pad-enga ging surfaces and having substantiallythe same shape as said pad engaging surfaces.

According to a preferred embodiment of this invention, the lower support member is foraminous, and the fibers are removed by establishing a pressure differential across the support member. Preferably,'the pres sure differential is established by directing air under positive pressure through the foraminous support member from the-lower surface thereof, and establishing a partial vacuum from above the upper surface of the fibrous web. Preferably, the fibers which are removed from the-support member are directed into the web I forming-device in which is formed the air laid fibrous weight pads, (e.g.,over 65 oz. per yd), cannot easily be formed in such three-dimensional compartments. To fur'therexplain, at commercial speeds and forming distances a high pressure. drop. must be established through the compartments to deposit such a high basis weight of fiberstherein. This high pressure drop excessively densities the fiber layer within the compartments before the requisite weight of fibers is deposited therein to render further formation difficult, if not impossible.

U.S. Pat. No. 3,661,680, assigned to. Riegel Textile Corporation, discloses an apparatus for forming disposable diapers in which a continuous fibrous web is separated into discrete web sections by removing narrow transverse bands of fibers from the continuous web. The apparatus includes an outer, rotating shell having a transverse slot therein. A stationary vacuum chamber having a slot therein is mounted within the outer shell. As the slot in the outer shell rotates into alignment with the slot of the vacuum chamber, thevacuum applied through the vacuum chamber will be effective to remove a narrow transverse band of fibers from the continuous web. This apparatus is acceptable for removing narrow transverse sections from a continuous web; however, practical machine design considerations impose dimensional limitations on the size of the outer shell which renders this means of removing fibrous web sections somewhat limited. For example, it would be 'web from which the discrete fibrous pads are formed.

. The air-laid fibrous web can be formed by any conventional web forming device, such as the Rando- Webber manufactured by Curlator Corporation of Rochester, New York. In addition, a multiplicity of fibrous webs can be formed in separate devices, and

these webs can be superimposed upon each other totured by multiple air-laying devices, In addition, the

- countered by forming pads in such compartments.

Other objects and advantages of this invention will become apparent upon reading the detailed description which follows, taken in conjunction with the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, side elevation view of a preferred apparatus of this invention; and

FIG. 2 is a schematic, isometric view showing various stages of formation of a discrete, fibrous pad from an air-laid fibrous web.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring to FIG. 1, the pad forming apparatus of this invention forms discrete fibrous pads 12 from an air-laid fibrous web 14 manufactured in any suitable web-forming device, such as the Rando-Webber, manufactured by Curlator Corporation of Rochester, NY.

The pad-forming apparatus 10 includes a plurality of pad-forming shoes 16 mounted on an endless conveyor 18, and the endless conveyor 18 is positively driven in the direction indicated by arrow 20 by any conventional drive means (not shown). Each pad-forming shoe 16 has a pad-engaging surface 17 of substantially the same shape as a fibrous pad to be formed. The fibrous web 14 is directed into the pad forming apparatus 10 on a foraminous support member 22, which, in the preferred embodiment of this invention is the foraminous forming surface upon which the air-laid fibrous web 14 is formed.

The continuous fibrous web 14 in conveyed on the foraminous support member 22 through a pad-forming region in which air under positive pressure is directed through the support member from a manifold 26 which is positioned below said support member. In addition, the pad-forming region includes a vacuum chamber 28 positioned above said support member, and the vacuum chamber is connected to a suitable vacuum source, such as a fan 29. 1

Referring to FIGS. 1 and 2, the fibrous web 14 is confined between the foraminous support member 22 and the pad-engaging surfaces 17 as said web is directed through the pad-forming region. A pressure differential is established through the foraminous support member 22 by directing air under positive pressure through the manifold 26, and by establishing a partial vacuum in vacuum chamber 28 through operation of fan 29. This pressure differential effects removal of the sections of the fibrous web 14 which are unconfined, to thereby form discrete fibrous pads 12 underlying the padengaging surfaces 17.

The foraminous support member 22 includes a section 23 which diverges from the pad-engaging surfaces 17 of the pad-forming shoes 16 at the downstream end of the pad-forming region to effect separation of the pad-engaging surfaces 17 from the formed fibrous pads 12. A partial vacuum is applied from below the foraminous support member 22 in this diverging section 23 through a vacuum box 32 to establish allegience of the formed pad 12 for the foraminous support member 22. The discrete fibrous pads 12 can then be directed to converting equipment (not shown) to permit use of said pads in the formation of sanitary products, such as disposable diapers, sanitary napkins and the like.

Preferably, the fibers which are removed through vacuum source 28 in the pad-forming region are directed back into the fiberizing device to be utilized in the forming of the fibrous web 14. I

Several modifications can be made within the scope of this invention. The pad-forming shoes 16 can be secured, or manufactured integral with, a cylindrical conveyor, as opposed to fastening the pad-forming shoes to the endless conveyor 18. The foraminous support member 22 can be replaced with an air-impervious support member. If the support member is impervious, the unconfined fibrous web regions can be removed by directing air under pressure across the upper surface of the support member, since a partial vacuum cannot be established through said support member. The number of pad-forming shoes 16 which are in engagement with the fibrous web 14 within the pad-forming region at any instant of time is, within practical limits, a matter of design choice. For example, the equipment can be designed so that only one pad-forming shoe 16 cooperates with the support member 22 to confine the fibrous web, at any instant of time, within the pad-forming region 25. The specific shape of the pad-engaging surfaces 17 is a matter of design choice, and is dictated by the specific shape of the fibrous pads to be formed. The fibrous web 14 can be formed as a continuous fibrous web or as discrete, separate web sections.

What is claimed is:

l. A method for forming at least one discrete fibrous pad having a predetermined shape from an air-laid fibrous web, said method comprising the steps of:

A. confining said fibrous web between a support member and at least one discrete surface to leave sections of said web unconfined, each discrete surface having a shape of a discrete fibrous pad to be formed; and

B. subjecting the unconfined sections of said web to a stream of gas for removing said unconfined sections from said web to form discrete fibrous pads having substantially the same shape as each discrete surface.

2. The method according to claim 1, including the step of confining said web between said support member and a plurality of spaced discrete surfaces to leave web sections between said discrete surfaces unconfined, and subjecting the unconfined web sections between the spaced discrete surfaces to a stream of gas for removing said unconfined sections from the web to form a plurality of spaced, discrete fibrous pads having substantially the same shape as the discrete surfaces.

3. The method according to claim 1, wherein said support member is foraminous, and said stream of gas is created by establishing a pressure differential through said support member.

4. The method according to claim 3, wherein said pressure differential is established by directing a gas under positive pressure through said support member from below said support member and establishing a partial vacuum from above said support member. 

1. A mEthod for forming at least one discrete fibrous pad having a predetermined shape from an air-laid fibrous web, said method comprising the steps of: A. confining said fibrous web between a support member and at least one discrete surface to leave sections of said web unconfined, each discrete surface having a shape of a discrete fibrous pad to be formed; and B. subjecting the unconfined sections of said web to a stream of gas for removing said unconfined sections from said web to form discrete fibrous pads having substantially the same shape as each discrete surface.
 2. The method according to claim 1, including the step of confining said web between said support member and a plurality of spaced discrete surfaces to leave web sections between said discrete surfaces unconfined, and subjecting the unconfined web sections between the spaced discrete surfaces to a stream of gas for removing said unconfined sections from the web to form a plurality of spaced, discrete fibrous pads having substantially the same shape as the discrete surfaces.
 3. The method according to claim 1, wherein said support member is foraminous, and said stream of gas is created by establishing a pressure differential through said support member.
 4. The method according to claim 3, wherein said pressure differential is established by directing a gas under positive pressure through said support member from below said support member and establishing a partial vacuum from above said support member. 